van der Knaap E, Tanksley S D
Department of Plant Breeding, Department of Plant Biology, 245 Emerson Hall, Cornell University, Ithaca, NY 14853-1902, USA.
Theor Appl Genet. 2003 Jun;107(1):139-47. doi: 10.1007/s00122-003-1224-1. Epub 2003 Mar 21.
The heirloom tomato cultivar Yellow Stuffer produces fruit that are similar in shape and structure to fruit produced by the bell pepper varieties of garden pepper. To determine the genetic basis of this extreme fruit type in tomato, quantitative trait loci (QTL) analysis was performed on an F(2) population derived from a cross between Yellow Stuffer and the related species, Lycopersicon pimpinellifolium, which produces a small, round fruit typical of most wild species. F(2) plants were analyzed for both fruit size and the degree to which their fruit resembled the bell pepper. Three QTL were determined to influence bell pepper shape and seven QTL influenced fruit mass. The map positions of all three bell shape and six out of seven fruit size QTL appear to be allelic to components of fruit morphology analyzed in this population and to major fruit morphology QTL reported previously, adding support to the hypothesis that the majority of fruit size and shape variation in cultivated tomato is attributable to allelic variation at a limited number of loci. However, novel loci controlling components of fruit morphology, such as elongated fruit shape, bumpiness, number of seed per fruit and flowers per inflorescence were identified in this study as well. The three bell shape loci involved are: bell2.1, bell2.2 and bell8.1, and appear to correspond to locule number2.1 ( lcn2.1) and fruit weight 2.2 ( fw2.2) and fruit shape 8.1 ( fs8.1), respectively. The Yellow Stuffer alleles at lcn2.1 and fw2.2 increase locule number and fruit size, respectively, hence contributing to the overall bell pepper shape. The Yellow Stuffer allele at fs8.1 causes convex locule walls, giving the extended, bumpy shape characteristic of bell peppers. In addition, most fruit size QTL correspond to loci controlling number of flowers per inflorescence and/or stem-end blockiness. Comparisons among previously identified fruit morphology loci in tomato, eggplant and pepper suggest that loci affecting several aspects of fruit morphology may be due to pleiotrophic effects of the same, orthologous loci in these species. Moreover, it appears that the evolution of bell pepper-shaped tomato fruit may have proceeded through mutations of some of the same genes that led to bell pepper-type fruit in garden pepper.
传统品种的番茄“黄馅”所结出的果实，在形状和结构上与甜椒品种的果实相似。为了确定番茄这种极端果实类型的遗传基础，对由“黄馅”与相关物种潘那利番茄杂交产生的F2群体进行了数量性状位点（QTL）分析，潘那利番茄结出的是大多数野生品种典型的小而圆的果实。对F2植株的果实大小以及果实与甜椒的相似程度进行了分析。确定有3个QTL影响甜椒形状，7个QTL影响果实重量。所有3个钟形QTL以及7个果实大小QTL中的6个的图谱位置，似乎与该群体中分析的果实形态组成部分以及先前报道的主要果实形态QTL等位，这支持了以下假设：栽培番茄中大多数果实大小和形状变异可归因于有限数量位点的等位变异。然而，本研究也鉴定出了控制果实形态组成部分的新位点，如细长的果实形状、凹凸不平、单果种子数和每花序花朵数。涉及的3个钟形位点为：bell2.1、bell2.2和bell8.1，似乎分别对应于心皮数2.1（lcn2.1）、果实重量2.2（fw2.2）和果实形状8.1（fs8.1）。lcn2.1和fw2.2处的“黄馅”等位基因分别增加了心皮数和果实大小，因此有助于形成整体的甜椒形状。fs8.1处的“黄馅”等位基因导致心皮壁凸起，赋予了甜椒特有的细长、凹凸不平的形状。此外，大多数果实大小QTL对应于控制每花序花朵数和/或果梗端块状化的位点。对番茄、茄子和辣椒中先前鉴定的果实形态位点的比较表明，影响果实形态多个方面的位点可能是由于这些物种中相同直系同源位点的多效性效应。此外，似乎甜椒形状番茄果实的进化可能是通过一些与导致甜椒品种中甜椒型果实相同的基因突变而进行的。
